问题
I had a Yii installation that was working fine up until today. I installed updates on my machine today after which this error was being thrown on all pages:
PHP Fatal Error – yii\base\ErrorException
Uncaught Error: Call to undefined function yii\web\mb_strlen() in /application/vendor/yiisoft/yii2/web/ErrorHandler.php:404
I ran composer update but the error persists.
I am using yii 2.0.7 on PHP 7 on Ubuntu 14.04. How do I fix this?
回答1:
The error is a bit of a red herring since mb_strlen() is actually part of the mbstring php extension and not a function in yii2.
In php5 mbstring was part of libapache2-mod-php5.
It seems to be missing from libapache2-mod-php7. To fix this install the php7.x-mbstring package where x is your version:
sudo apt install php7.x-mbstring
You may need to restart Apache after this install.
回答2:
For PHP7.1
Debian flavours
sudo apt-get install php7.1-mbstring
RedHat flavours
sudo yum install php7.1-mbstring
回答3:
CentOS/RHEL-based
To get a list of available modules to check the version you need is available:
yum search mbstring
Installing mbstring module:
sudo yum install php-mbstring
This will install the correct version for you for your current php installation.
来源：https://stackoverflow.com/questions/35756821/call-to-undefined-function-mb-strlen-on-php-7-ubuntu-14-04